The invention relates to a variable dispersion compensator for use in optical communication systems and optical measurement fields.
In optical communication systems using optical fibers, there has occurred wavelength dispersion of the optical fibers during signal light transmission. Therefore, compensation for the wavelength dispersion has been needed. One of the means for compensating this optical-fiber wavelength dispersion is a variable dispersion compensator that uses an optical multiple reflector made of a glass base having two reflecting faces opposed to each other. This variable dispersion compensator has been already reported in U.S. Pat. No. 5,930,045.
In general, such a variable dispersion compensator is often disposed in the cabinet of an optical amplifier. Accordingly, when, for example, a high-power laser or an erbium-doped fiber making the optical amplifier generates heat, the temperature in the cabinet of the optical amplifier rises to change the ambient use temperature of the variable dispersion compensator.
The U.S. Pat. No. 5,930,045 has proposed that a temperature sensor detects the temperature of the optical multiple reflector, and a controller controls, based on the temperature detected, a heating/cooling unit for controlling the temperature of the optical multiple reflector to adjust the temperature of the optical multiple reflector.
In this proposal, however, there is no disclosure which locations of arrangement and what methods of fixing are most desirably adopted to operate the temperature sensor and the heating/cooling unit with efficiency and prevent disturbing the function of the wavelength division multiplexed light.
Also in the foregoing U.S. Pat. No. 5,930,045, there is no disclosure as to the conception of concrete measures that can suppress vibrations of the optical multiple reflector even if the cabinet accommodating the variable dispersion compensator vibrates.
An object of the present invention is to provide a variable dispersion compensator which can suppress a change in the optical characteristics from changes in temperature and vibrations to exert favorable characteristics with stability.
To achieve the foregoing object, the present invention provides a variable dispersion compensator comprising: an optical incidence/output device for propagating wavelength division multiplexed light, composed of an optical fiber and a lens; an optical multiple reflector on which the wavelength division multiplexed light emitted from the optical incidence/output device is incident for repetitive reflections between a transmitting face and a reflecting face thereof; and a movable optical reflection device for reflecting the wavelength division multiplexed light emitted from the optical multiple reflector toward the optical multiple reflector, the movable optical reflection device composed of a lens and a reflecting element and being capable of controlling the distance from the optical multiple reflector. Here, a temperature adjusting element is arranged via a thermal-conductive elastic member on a surface of the optical multiple reflector at a portion where no drop occurs in the intensity of the wavelength division multiplexed light incident/emitted.